Alkali Metals, series of six chemical elements in group 1 (or Ia) of the periodic table (see Periodic Law). They are soft compared to other metals, have low melting points, and are so reactive that they are never found in nature uncombined with other elements. They are powerful reducing agents, that is, they give up an electron easily, and react violently with water to form hydrogen gas and hydroxides, or strong bases. The alkali metals are, in order of increasing atomic number, lithium, sodium, potassium, rubidium, cesium, and francium. Francium exists only in a radioactive form.